Koos Boeve

39 8th TNM classification prognostic value in oral cancer (DFS) was defined as the time until local, regional or distant recurrence or the last follow-up within 3 years after the start of the initial treatment. Death was censored and did not count as a DFS event. Table 1. Population characteristics Variables n (%) Total patients 211 (100) Gender Male 118 (56) Female 93 (44) Age at diagnosis Mean (SD) 62 (13) (years) Range 25 to 94 Site Tongue 108 (51) Gum 14 (7) Floor of mouth 64 (30) Cheek mucosa 7 (3) Retromolar area 12 (6) Other 6 (3) cT status (7 th ) 1-2 189 (90) 3-4 22 (10) cN status (7 th ) cN+ 50 (24) cN0 161 (76) Histopathological characteristics Tumour thickness (mm) Median (IQR) 6.00 (3.3 to 9.0) Range 0.1 to 20.0 Perineural invasion 35 (17) Lymphovascular invasion 19 (9) Involved margins (<1 mm) 32 (15) PO(C)RT 72 (34) Follow-up (months) Median (IQR) 64 (30 to 99) Range 0 to 193 Recurrences Locoregional recurrence 13 (6) Regional recurrence 26 (12) Distant metastasis 6 (3) Death Due to disease 36 (17) Overall 68 (32) Abbreviations: OSCC, oral squamous cell carcinoma; SD, standard deviation; IQR, interquartile range; PO(C)RT, postoperative chemo or radiation therapy.